Investigation of an outbreak of foodborne illness caused by norovirus GⅡ.17

ObjectiveTo find out the cause and pathogenic factors of acute gastroenteritis occurred in a research institute in Beijing, 2018.

MethodsThe clinical manifestations and the distribution of the patients were described with descriptive epidemiological method, and case control study was used to find out the suspected exposed meals and foods. Field hygiene survey was carried out. Samples from the cases and foods were collected for the PCR detection of norovirus, and partial gene sequencing of RNA-dependent RNA polymerase region was performed for the positive strains.

ResultsA total of 107 cases were found with the main symptoms of diarrhea (100%), abdominal pain (79%), vomiting (74%) and nausea (68%). The results of the epidemiological investigation demonstrated that the lunch of March 21 (provided by a food delivery company) was the suspected meal, and sauce elbow was the suspected food, which might be cross-contaminated during the preparation and without effective heating before provision. Seventeen strains of norovirus GⅡ were detected from 26 anal swabs and stool samples. Polymerase region gene sequencing showed that 8 strains shared 100% consistent nucleotide sequence, and NCBI blast showed that the 8 strains shared 99% homology with the GⅡ.17 variant strain 41 621 reported in Guangzhou.

ConclusionThe sauce elbow contaminated by norovirus was the main infection source of this outbreak of foodborne illness. It is suggested that we should strengthen the supervision and management of food production practices in catering industry for the prevention of recurrence of similar incidents.